Furan 2 does not have methylene blue in it.. It is only Nitrofurazone and Furazolidone.

Jungle Fungus clear has nitrofurazone and furazolidone and something called potassium dichromate which is a toxic strong mineral acid compound used in pyrotechnics and explosives.. it can also be used to clean glassware, is a component in cement, can be used to stain woods and tan leather, and is used in photography. It can cause dermatitis in humans, is carcinogenic, has been shown to kill much larger animals than bettas at pretty small concentrations, and has special environmental disposal laws because of how it effects aquatic life (meaning you can't just flush the fish water or pour it out in your yard). I have no idea what it's doing in a fish med. Because of this component, I would stay away from the Jungle and use the API brand, though I suppose if it doesn't kill the fish it would help to kill any bacteria because of its toxic/acidic nature.

I don't know how many mg of each is included in a dose of Jungle because I don't think they include it. You may be able to find out by contacting them directly. Since I haven't ever used it, I haven't bothered to seek additional info.